The Bush Decision

Bush will allow funding for research on stem cells already extracted from embryos. But his position has raised questions.

WHAT ARE THEY? A line is created by extracting cells from an embryo only a few days old; this destroys the embryo. Under the right conditions, cells will replicate, creating genetically identical cells.

65 THE NUMBER? Until last week, most scientists knew of only a dozen cell lines. National Institutes of Health experts now say they have tracked down at least 65 cell lines worldwide. All were created from leftover in-vitro fertilization embryos. But scientists question...